Microelectronic devices such as semiconductor devices are generally fabricated on and/or in substrates or wafers. In a typical fabrication process, one or more layers of metal or other conductive materials are formed on a wafer in an electroplating processor. The processor has a bath of electrolyte held in vessel or bowl, with one or more anodes in the bowl. Due to their microscopic size and chemical and electrical characteristics, microelectronic devices are highly sensitive to particle and chemical contamination. Consequently, the electrolyte must remain free of contamination, and have a chemical makeup within specified limits. Monitoring the chemical constituents and concentrations is important because variations in the electrolyte may degrade plating quality.
Electrolyte analysis systems have been developed for this purpose. These systems typically use voltammetry measurement techniques. One example of an electrolyte analysis system, as used for copper damascene electrolyte, is the Real Time Analysis system (RTA) available from Technic Inc., Inc., Cranston, R.I., USA. Similar systems are available from other manufacturers. These types of systems determine concentrations of inorganic constituents and organic additives in the electrolyte via AC and DC voltammetry analysis, using an electrode probe immersed in the electrolyte. However, the probe is highly sensitive to temperature and flow rate. Consequently, in the past use of these types of probes has required extensive use of various heat exchangers, insulated lines and other temperature control techniques, and a large buffer volume of electrolyte. The voltammetry process itself may apparently also create small copper particles in the electrolyte which may act as a contamination source. As a result, engineering challenges remain in designing improved electrolyte monitoring systems.